Preservation and conservation of ancient Theaceae germplasm from biological refuges in Vietnam

D. R. Winn[1]

Royal Botanic Gardens, Mrs Macquaries Road,Sydney, NSW 2000, Australia
[1] email: g_onebonobo@hotmail.com

The preservation and conservation of ancient Theaceae germplasm is of paramount importance as it promotes the survival of the all important genetic pool from which the currently extant Theaceae genera and species evolved. Both the traditional view, and the current and widely accepted hypothesis, regard North Viet Nam to be the home of most known Vietnamese Camellia species, and the only geographical region within Viet Nam which contains the yellow flowering representatives of the genus. As the mountains that delimit the Red River valley form the southern geographical continuation of the mountains of the ‘Camellia provinces of China’ it was thought, that the North to South speciation and radiation of Theaceae species (and Camellia) occurred here some time in the past. Only a relatively few ‘primitive’ South Vietnamese species of Camellia were known to science, perhaps the most prominent being C. piquetiana (Pierre) Sealy, C. krempfii (Gagnep.) Sealy and C. dormoyana (Pierre) Sealy.

The well tested scientific and empirical evidence shows that Theaceae and the member species of genus Camellia also occur in other geographically and climatically varied regions of South-East Asia. Adjacent to the southern and western borders of Viet Nam Camellia species can be found within the rainforests of Laos and in Eastern Cambodia. A number of Theaceae genera, but not Camellia are native to Mayanmar and to the rainforests of Thailand, Malaysia and Indonesia. One, and possibly two, Camellia species occur in the Philippines.

The 2002 re-discovery of the ‘extinct’ C. piquetiana (Pierre) Sealy by Australian scientists gave the existing Australian Camellia research a new impetus and helped to formulate a firm rationale for further scientific inquiry. The statement: ‘If a long lost, presumably ‘extinct’, plant species still existed and could be found, could there be others?’ became the basis for the ‘Project Camellia’ research project.

The scientific basis for ‘Project Camellia’ was the already formulated hypothesis which was later published by Orel & Marchant in 2006. It proposed a new interpretation of known facts which pertain to the origin of Theaceae and in particular to genus Camellia. The hypothesis considered the South Asian phyto-geographic region to be not only an important biological refuge but also a centre of genetic diversity for a large number of endemic species of ancient plants. The projection for the presence of ‘a large number of endemic species’, including those of family Theaceae, was based on then available data and the unpublished personal observations. These indicated that the long disputed centre of the origin for the genus Camellia may lay geographically further south than currently suggested, perhaps within the areas that now comprise southern Viet Nam, southern Laos, Cambodia, Thailand, parts of Mayanmar, the peninsular Malaysia, parts of Indonesian archipelago (Sumatra, Java, Borneo and Celebes) and the eastern and western geographical areas of the now submerged sub-continent of Sundaland see Fig. 1.

The hypothesis for the southern origin of Theaceae and the South to North radiation of Theaceae genera proposed the following scenario :- Prior to the rise of Himalaya, genus Camellia, together with other Theacea genera or possibly their precursors, formed an important floristic component in the understorey of the then extensive tropical rainforest, which covered large parts of South East Asia. This dense forest covered a vast territory, parts of which, due to repeated global glaciations and continuous tectonic activity, became episodically submerged, with large parts being separated from the Asian mainland. Evidence shows, that during the peak of the Last Glacial Maximum (in the Würm Glaciation Period, between 26,500 and 19,000 to 20,000 years ago), the size of this ancient rainforest was reduced by the spread of the dryer deciduous forests. The rainforest remnants survived, mainly in the East and also in the Western extremities of the Sundaland (Fig. 1.)

Thus the rainforests of Southern Viet Nam and the rainforests currently found on the Malay Peninsula, the Indonesian Archipelago and the Philippines may be the survivors of Sundaland and the period of time when the sea levels were 120 to 135 m lower than today. Other detailed studies add further valuable evidence  and seem to underpin the proposed hypothesis.

 Fig.1 The sub-continent of Sundaland during the Last Glacial Maximum around  20,000 years ago
(The Würm Glaciation Period).

Murray & Dorobek, 2009.

 It is thought, that the general South to North radiation of Theaceae and other rainforest species and genera occurred in response to the localised forces of evolution and natural selection which were engendered by fundamental changes in geography (tectonic and orogenic processes) and climatic conditions.

Due to the partially conflicting evidence and insufficient scientific data it remains unclear at what point in time the proposed Northern radiation of Theaceae and other species began. As we know, there have been at least four glaciation episodes within the last 600,000 years (Table 1.). It is possible, that the South to North radiation of the said rainforest genera occurred earlier (within a period of some 600,000 years) and continued sporadically when the prevailing geological and climatic condition were optimal. (

Table  1  Glaciation Periods in overview

(Murray & Dorobek, 2009)

 The currently available molecular evidence and the accompanying morphological data support the proposed hypothesis in general terms. The already known, as well as the newly discovered South Vietnamese Camellia taxa are relictual, warm climate species, suited to warm, rainforest habitats with low light requirement. They also possess morphological characteristics common to most tropical rainforest plant species e.g., the large adult leaves, prominent and sunken adaxial leaf venation, soft and pedunculate juvenile foliage, prominent leaf drip tips and mature seed with a short time span of viability. It should be noted that Theaceae and Camellia species with small, rigid leaves and thickened leaf cuticles, all morphological traits which may protect the foliage against cold, water loss and higher light levels, were not found.

A systematic search of the Da Lat Plateau and the adjacent Lang Biang Massif was the logical first step in locating the presumed ‘large number of endemic Camellia (and other Theaceae) species’. This search was rewarded almost immediately by the discoveries of a large number of hitherto unknown Eurya, Camellia and Polyspora (Gordonia)species. These unexpectedly abundant finds suggest that the Da Lat Plateau and the neighbouring Lang Biang Massif may, in the past, have formed the northern boundary of the tropical area of origin for the family Theaceae and genus Camellia.

The discoveries of new and to science yet unknown Camellia and Theaceae species clearly highlights the need for in situ and other forms of conservation and preservation. Good examples of species in need of protection are the newly discovered and recently published C. dongnaiensis Orel, C. maiana Orel, C. luteocerata Orel and C. cattienensis Orel. To this date fewer than 30 individual plants of each of these taxa have been found, some being described from a single individual only. There are also a number of newly found and un-described South Vietnamese Camellia species which are being investigated. In addition several new Polyspora (Gordonia) and Eurya species are also in the process of being described. All of these new finds are on endangered or critically endangered lists due to small individual numbers and habitat destruction.

Recent changes in the quarantine laws of Australia prevent the importation of live materials of all Theaceae species, including Camellia,into Australia. Importation of Camellia seed with certain restrictions is still possible, but the supply is highly unreliable and most of the time seed is not available. The establishment of the Camellia Species Gardens near Da Lat City, Viet Nam was the direct outcome and reaction to this prohibition. It is hoped, that the already collected and the yet to be discovered Theaceae germplasm grown in the protected environment of the Gardens will, in time, furnish materials needed for further scientific research and also produce viable propagation materials. Seedling production of limited quantities and of selected Camellia and Theaceae species will be utilized in restoration work that will be carried out in carefully selected areas of the rainforest.

The proposed establishment of new Botanic Gardens in the Bidoup-Nui Ba National Park, Lam Dong Province, Viet Nam, under the auspices of the Royal Botanic Gardens in Sydney, will add further impetus to the preservation and conservation of the rare and endangered Theaceae and Camellia species of Viet Nam. The project, although still in its early stages, will give further impetus to the ongoing preservation and conservation effort to safeguard the unique Theaceae and Camellia genera and species of Viet Nam.

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